Along with the spread of electronic mail, electronic documents and the WWW, the task of extracting and managing just the necessary information from electronic documents, electronic mail and web pages has increased. Just the necessary information must frequently be recorded such as writing in a memo-book the location and the time where a conference is being held from electronic mail about a future conference (example 1); writing down on paper a portion of an interesting web page (example 2); or writing a portion of measurement values from an electronic file of experimental data into experiment memos (example 3). In any case, secondary information such as memos must be made from primary information comprised of the original electronic file.
However not all of the primary information is being recorded as secondary information so that in many cases a user will want to refer to primary information from the secondary information. In example 1, a user may want to check the original electronic mail to find information other than the location and day of the conference, such as sender of the conference invitation mail and the objective of the conference. In example 2, the user may want to again check the contents of the web page comprising the source of the information. In example 3, the user may want to check the electronic file of experimental data in order to reevaluate the values measured in the experiment later on.
In these type of situations where referring to primary information from the secondary information, the user must be able to access and pinpoint primary information in page units rather than in document units, in cases where the primary information is a long document or a long web page.
Devices for forming index information such as keywords in documents and periodical information incorporate technology for automatically forming timing index information such as for saving document files and closing document display windows. These devices also include technology for copying a page each time the WWW page of a new URL is displayed, and linking that page to index information for that page, and storing it (See for example, JP 2000-285134 A).
These devices also include technology for linking a specified, defined word sequence (string) with page information on where that sequence appears and recording it into a table. This technology is equivalent to automatically forming an index of electronic documents (topic list) (See for example, JP 1996-319873 A).
Technology has also been contrived for a pen type input device (digital pen) capable of electronically acquiring the track of the pen tip in order to enter memos or memos on paper as secondary information. The digital pen may for example be technology such as the “Anoto Pen” developed by the Anoto company of Sweden (See for example, W0 01/71473).